<!DOCTYPE html>
<html>

	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>

	<body>
		<table id="box">
			<tr>
				<td>A</td>
				<td>B</td>
			</tr>
			<tr>
				<td>C</td>
				<td>E</td>
			</tr>
		</table>
		<script>
			var tbl = document.getElementById("box")
			tbl.rows[0].cells[1].style.backgroundColor = "red"
		</script>
	</body>

</html>